Tone production system in electronic musical instrument



Jan. 12, 1965 AKIRA YOKOYAMA TONE PRODUCTION SYSTEM IN ELECTRONICMUSICAL. INSTRUMENT 3 Sheets-Sheet 1 Filed April 18, 1963 ON w fi N W477a rn e Jan. 12, 1965 AKIRA YOKOYAMA 3,16 ,022

TONE PRODUCTION SYSTEM IN ELECTRONIC MUSICAL INSTRUMENT Filed April 18,1963 3 Sheets-Sheet 2 FIG.2.

Jan. 12, 1965 AKIRA YOKOYAMA 3,165,022

TONE PRODUCTION SYSTEM IN ELECTRONIC MUSICAL INSTRUMENT Filed April 18,1965 3 Sheets-Sheet 5 L I i q 26 I 5 I J4 van 1 r AKIKA (0/40YA M AUnited States Patent 3,165,022 T0 l3 PRODUCTION SYSTEM IN ELECTRONICMUSICAL INSTRUMENT Akita Yokoyama, Yaou Electric Co., Ltd., 1116Suenaga, Kawasaki-shi, Kanagawa-ken, Japan Filed Apr. 18, 1963, Ser. No.274,017 4 Claims. (Cl. 84-405) This invention relates to a toneproduction apparatus such as an electronic organ or similar electronicmusical instrument. More particularly, the invention is concerned withthe sound production system in such musical instruments wherein apermanent magnet is adapted to come in and out of contact with a toneproducer of ferromagnetic material thereby controlling the production ofsound.

Generally, as the fundamental requirements for keyboard instruments,there may be considered as instantaneous impulsive response of avibrating string or reed to hammer action of a keyboard or manual; theabsence of rebound or objectionable echo, and a quick termination ofvibration of the string or reed upon release of the key.

With conventional keyboard instruments, it has hitherto been difficultto meet these requirements without involving complex and expensivedesign considerations such as given to a grand piano. Moreover, with theconventional type keyboard instruments, it has been impossible to makethe equipment compact and space-saving in consideration of the abovetechnical requirements.

Whereas, it is an object of the present invention to provide asimplified, compact and low-cost keyboard instrument capable ofimpulsive tone production which will substantially fulfill theafore-mentioned fundamental requirements. To accomplish the object, theinvention contemplates application of its principles to a relativelylowcost electronic organ or similar electronic musical instrument.

The characteristic features of the invention lie primarily in theconstruction of such an electronic keyboard instrument in which thekeyboard or manual is provided with a plunality of permanent magnetswhich, at the rest position of the keyboard, remain in contact withcorresponding tone producing members or vibrating reeds of ferromagneticmaterial mounted on a base and which, when the key is depressed,separate from the tone producing members.

In a preferred mode of the invention, the permanent magnet justmentioned may be a rubber magnet.

With this construction, when the key is depressed, the tone producingmember is released from the permanent magnet, followed by impulsiveexcitation into vibration and is so maintained until this vibrationattenuates progressively with time. If the key is released while thetone producing member is still in vibration, the permanent magnet is"attracted to the tone producing member thereby rapidly stopping thevibration. Attraction of the magnet to the tone producing member takesplace of course as soon as the key is released after vibration isceased.

In accordance with an embodiment of the invention, there may be providedan electrode in close vicinity to the tone producing member so that acapacitor is formed therebetween. As can be readily understood to thoseskilled in the art, this capacitor undergoes static variation accordingto vibration of the tone producing member. Therefore, by connecting thecapacitor circuit to a suitable electrical device, it is possible toobtain a sound corresponding to a variation in static capacity of thecircuit by way of a speaker. The electrode, as it is obvious, may bereplaced by a coil or other suitable means.

For a more complete understanding of the nature and scope of theinvention, as concisely defined in the appended claims, reference may bemade to the following detailed description of a specific embodimenttaken in conjunction with the accompanying drawing in which:

FIG. 1 is a perspective view of a keyboard instrument embodying theinvention with a portion cut away to show the internal structure.

FIG. 2 is a magnified perspective view of the essential portion of thestructure in FIG. 1.

FIG. 3 is a cross-sectional view taken on the line 33 of FIG. 1.

FIG. 4 is a schematic diagram illustrating an application of the toneproduction system according to the invention.

Reference being now had to FIGS. 1 through 4, inclusive, a mounting base1 is shown as extending longitudinally of and parallel with a case 2. Onthe mounting base 1, there is provided a fulcrum rail 3 extending at thecenter and lengthwise thereof to support a plurality of keys 4. Each ofthe keys 4 is attached at its rear end with a magnet mounting plate 5.This mounting plate may alternatively be a bar or rod. The magnetmounting plate 5 is provided at the other end with a permanent magnet 6and with a balancing weight 7, the former being attached to the bottomand the latter to the top of the plate, respectively.

Designated by the numeral 9 is a coil spring which is secured at one endin a recess 8 provided in thebottom pant of the key 4 in front of thesupport rail 3 and at the other end in a similar recess 10 provided inthe mounting base 1 at corresponding position. The key 4 is furtherprovided at the bottom part with a groove 11 to engage the top of thesupport rail 3, which is cone-shaped as viewed from the side, and at thetop part with a recess 12. The numeral 13 designates a small holesprovided between the groove 11 and the upper recess 12.

A pin 14 is adapted to secure the key 4 to the support rail 3 and isitself fixed at an end to the rail 3. A coil spring 15 is adapted tofacilitate the engagement of key 4 with rail 3 under tension.

On the mounting base 1, there are provided stoppers 18 and 19 attachedwith felts 16 and 17, respectively, the one being located in front andthe other in rear of the support rail 3. These stoppers are adapted tolimit the range of motion of the key 4.

On the mounitng base 1, there is further provided an electricalinsulating board 20 underneath the permanent magnet 6. The insulatorboard 20 is mounted with a support member 21 of electrical insulatingmaterial. On top of this support member is provided a tone producingmember, -i.e. vibration reed 22 which is fastened thereto by means of awooden screw 23 and a washer 24.

The vibration reed 22 is normally held at its free end in contact withthe permanent magnet 6 at the rest position of the keyboard.

Now, in operation of the tone production apparatus in accordance withthe invention, as the key 4 is depressed against tension in the coilspring 9, the permanent magnet 6 moves upward to a point where thetension of the vibration reed 22 overcomes the attraction of the magnet6, with the result that the magnet and the reed are forced apart. Thisis when the reed 22 begins self-vibration to produce a sound. As the key4 is released, the permanent magnet 6 is brought back to its originalposition by means of the coil spring 9 and the balancing weight 7. Thereed vibration can be stopped immediately after release of the keybecause of the attraction of the magnet to the reed.

As shown in the drawings, the insulator board 20 is further providedthereon with a fixed electrode 26 having a lead connecting terminal 25.The vibration reed 22 coacts with the fixed electrode 26 to form acapacitor. Quite obviously, this capacitor is subjected to static varia-9 tion according to the amplitude of the reed vibration. The capacitorcircuit, therefore, may be connected to an oscillator 28 coupled with anamplifier 27 to which a speaker 29is connected. In this manner, it ispossible to obtain a tone color corresponding to the vibration of thereed22 through the speaker 29.

Obviously, the vibration reed 22 varies in size with the pitch of sounddesired.

It will be understood from the foregoing description of the inventionthat the sound production system according to the inventionsubstantially achieves the important prerequisites of a keyboard musicalinstrument-an instantaneous impulse to the vibration reed with a minimumforce of depression of the key, no reboun or objectionable echo, and aquick stop to the reed vibration upon release of the key. Furthermore,in accordance with the invention, it is possible to render theinstrument as a Whole substantially compact and light weight therebypermitting of its location in minimum space.

Since certain changes may be made in the above described construction,and diiierent embodiments may be made of the invention without departingfrom the spirit or scope thereof, it is intended that all the mattercontained in the above description and shown in the accompanyingdrawings shall be considered as illustrative and not in a limitingsense. And, it is to be understood that without further analysis of theprinciples of the invention herein, those skilled in the art may easilyapply the principles set forth in the following claims to a variety ofelectronic keyboard instruments.

Whatis claimed is:

1. In an electronic musical instrument, a tone production systemcomprising, in combination, a plurality of vibratory reeds ofparamagnetic material, a corresponding number of keys constituting akeyboard and each associated with a respective reed; means fixedlymounting each reed at one end thereof for free vibnation of the reedrelative to such one end; means mounting said keys for movement betweena rest position and a depressed position; each key having one endoverlapping the associated reed; land a plurality of permanent magnetseach directly secured to said one end of the respective reed key; eachmagnet, in the rest position of its associated key, firmly engaging avibratory portion of the associated reed to clamp the latter againstvibration; each magnet, upon depression of its associated key, initiallydeflecting the associated reed about said fixed one end thereof and thenreleasing the associated reed for free vibration about said fixed oneend; each magnet, upon release of its associated key, re-engaging thevibratory portion of the associated reed to terminate the free vibrationof the latter.

2. A tone production system according to claim 1, in which saidpermanent magnets are rubber magnets.

3. In an electronic musical instrument, a tone production system asclaimed in claim 1, said means mounting said keys engaging said keysintermediate their ends; and means biasing each key to the restposition; said one end of each key, in the rest position of the key,extending in laterally spaced, substantially parallel longitudinalalignment to the associated reed.

4. In an electronic musical instrument, a tone production system asclaimed in claim 1, in which said one end of each key comprises arelatively elongated strip of mater ial extending above the associatedreed; the respective permanent magnet being secured to the free end ofsaid strip of material on the undersurface of the latter; and a Weightsecured to the free end of said strip of material on the upper surfacethereof.

References Cited by the Examiner UNITED STATES PATENTS 2,780,126 2/57Modeer 84-l.15 3,026,587 3/62 Spencer 317201 3,042,205 7/62 Merwin317-201 3,077,137 2/63 Miessner 841.15 X

LEO SMILOW, Primary Examiner.

1. IN AN ELECTRONIC MUSICAL INSTRUMENT, A TONE PRODUCTION SYSTEMCOMPRISING, IN COMBINATION, A PLURALITY OF VIBRATORY REEDS OFPARAMAGNETIC MATERIAL, A CORRESPONDING NUMBER OF KEYS CONSTITUTING AKEYBOARD AND EACH ASSOCIATED WITH A RESPECTIVE REED; MEANS FIXEDLYMOUNTING EACH REED AT ONE END THEREOF FOR FREE VIBRATION OF THE REEDRELATIVE TO SUCH ONE END; MEANS MOUNTING SAID KEYS FOR MOVEMENT BETWEENA REST POSITION AND A DEPRESSED POSITION; EACH KEY HAVING ONE ENDOVERLAPPING THE ASSOCIATED REED; AND A PLURALITY OF PERMANENT MAGNETSEACH DIRECTLY SECURED TO SAID ONE END OF THE RESPECTIVE REED KEY; EACHMAGNET, IN THE REST POSITION OF ITS ASSOCIATED KEY, FIRMLY ENGAGING AVIBRATORY PORTION OF THE ASSOCIATED REED TO CLAMP THE LATTER AGAINSTVIBRATION; EACH MAGNET, UPON DEPRESSION OF ITS ASSOCIATED KEY, INITIALLYDEFLECTING THE ASSOCIATED REED ABOUT SAID FIXED ONE END THEREOF AND THENRELEASING THE ASSOCIATED REED FOR FREE VIBRATION ABOUT SAID FIXED ONEEND; EACH MAGNET, UPON RELEASE OF ITS ASSOCIATED KEY, RE-ENGAGING THEVIBRATORY PORTION OF THE ASSOCIATED REED TO TERMINATE THE FREE VIBRATIONOF THE LATTER.